What are general observations in electrolysis?

• A. The bulb will light, a metal is formed on the cathode, fizz of gases produced
• B. The solution will turn blue
• C. No reaction occurs
• D. The temperature will drop rapidly

Answer: (A)

When an electric current passes through an electrolyte, ions move to the electrodes and are discharged: cations gain electrons at the cathode and metal can be deposited there, while anions are discharged at the anode. This flow of charge through the circuit makes the connected bulb light, showing that a current is passing. If the electrolyte contains metal ions, you can see a metal layer form on the cathode due to reduction. In aqueous solutions, water can also be discharged, producing gases that fizz at the electrodes. So the combination of the bulb lighting, a metal coating on the cathode, and gas bubbles is a typical set of observations in electrolysis. The other options don’t describe these general signs: color change to blue isn’t universal, no reaction isn’t right when current is flowing, and a rapid temperature drop isn’t expected.